su.c

自己根据lkd和情境分析

			retval = -EAGAIN;
#endif
			break;
		}
		if (!(info->flags & ASYNC_CALLOUT_ACTIVE) &&
		    !(info->flags & ASYNC_CLOSING) &&
		    (do_clocal || (serial_in(info, UART_MSR) &
				   UART_MSR_DCD)))
			break;
		if (signal_pending(current)) {
			retval = -ERESTARTSYS;
			break;
		}
#ifdef SERIAL_DEBUG_OPEN
		printk("block_til_ready blocking: ttys%d, count = %d\n",
		       info->line, info->count);
#endif
		schedule();
	}
	current->state = TASK_RUNNING;
	remove_wait_queue(&info->open_wait, &wait);
	if (extra_count)
		info->count++;
	info->blocked_open--;
#ifdef SERIAL_DEBUG_OPEN
	printk("block_til_ready after blocking: ttys%d, count = %d\n",
	       info->line, info->count);
#endif
	if (retval)
		return retval;
	info->flags |= ASYNC_NORMAL_ACTIVE;
	return 0;
}

/*
 * This routine is called whenever a serial port is opened.  It
 * enables interrupts for a serial port, linking in its async structure into
 * the IRQ chain.   It also performs the serial-specific
 * initialization for the tty structure.
 */
static int
su_open(struct tty_struct *tty, struct file * filp)
{
	struct su_struct	*info;
	int 			retval, line;
	unsigned long		page;

	line = MINOR(tty->device) - tty->driver.minor_start;
	if ((line < 0) || (line >= NR_PORTS))
		return -ENODEV;
	info = su_table + line;
	info->count++;
	tty->driver_data = info;
	info->tty = tty;

	if (serial_paranoia_check(info, tty->device, "su_open")) {
		info->count--;
		return -ENODEV;
	}

#ifdef SERIAL_DEBUG_OPEN
	printk("su_open %s%d, count = %d\n", tty->driver.name, info->line,
	       info->count);
#endif
	info->tty->low_latency = (info->flags & ASYNC_LOW_LATENCY) ? 1 : 0;

	if (!tmp_buf) {
		page = get_free_page(GFP_KERNEL);
		if (!page)
			return -ENOMEM;
		if (tmp_buf)
			free_page(page);
		else
			tmp_buf = (unsigned char *) page;
	}

	/*
	 * If the port is the middle of closing, bail out now
	 */
	if (tty_hung_up_p(filp) ||
	    (info->flags & ASYNC_CLOSING)) {
		if (info->flags & ASYNC_CLOSING)
			interruptible_sleep_on(&info->close_wait);
#ifdef SERIAL_DO_RESTART
		return ((info->flags & ASYNC_HUP_NOTIFY) ?
			-EAGAIN : -ERESTARTSYS);
#else
		return -EAGAIN;
#endif
	}
	
	/*
	 * Start up serial port
	 */
	retval = startup(info);
	if (retval)
		return retval;

	MOD_INC_USE_COUNT;
	retval = block_til_ready(tty, filp, info);
	if (retval) {
#ifdef SERIAL_DEBUG_OPEN
		printk("su_open returning after block_til_ready with %d\n",
		       retval);
#endif
		return retval;
	}

	if ((info->count == 1) &&
	    (info->flags & ASYNC_SPLIT_TERMIOS)) {
		if (tty->driver.subtype == SERIAL_TYPE_NORMAL)
			*tty->termios = info->normal_termios;
		else 
			*tty->termios = info->callout_termios;
		change_speed(info, 0);
	}
#ifdef CONFIG_SERIAL_CONSOLE
	if (sercons.cflag && sercons.index == line) {
		tty->termios->c_cflag = sercons.cflag;
		sercons.cflag = 0;
		change_speed(info, 0);
	}
#endif
	info->session = current->session;
	info->pgrp = current->pgrp;

#ifdef SERIAL_DEBUG_OPEN
	printk("su_open ttys%d successful...", info->line);
#endif
	return 0;
}

/*
 * /proc fs routines....
 */
static int
line_info(char *buf, struct su_struct *info)
{
	char		stat_buf[30], control, status;
	int		ret;
	unsigned long	flags;

	if (info->port == 0 || info->type == PORT_UNKNOWN)
		return 0;

	ret = sprintf(buf, "%u: uart:%s port:%lX irq:%s",
		      info->line, uart_config[info->type].name, 
		      (unsigned long)info->port, __irq_itoa(info->irq));

	/*
	 * Figure out the current RS-232 lines
	 */
	save_flags(flags); cli();
	status = serial_in(info, UART_MSR);
	control = info ? info->MCR : serial_in(info, UART_MCR);
	restore_flags(flags);

	stat_buf[0] = 0;
	stat_buf[1] = 0;
	if (control & UART_MCR_RTS)
		strcat(stat_buf, "|RTS");
	if (status & UART_MSR_CTS)
		strcat(stat_buf, "|CTS");
	if (control & UART_MCR_DTR)
		strcat(stat_buf, "|DTR");
	if (status & UART_MSR_DSR)
		strcat(stat_buf, "|DSR");
	if (status & UART_MSR_DCD)
		strcat(stat_buf, "|CD");
	if (status & UART_MSR_RI)
		strcat(stat_buf, "|RI");

	if (info->quot) {
		ret += sprintf(buf+ret, " baud:%u",
			       info->baud_base / info->quot);
	}

	ret += sprintf(buf+ret, " tx:%u rx:%u",
		       info->icount.tx, info->icount.rx);

	if (info->icount.frame)
		ret += sprintf(buf+ret, " fe:%u", info->icount.frame);

	if (info->icount.parity)
		ret += sprintf(buf+ret, " pe:%u", info->icount.parity);

	if (info->icount.brk)
		ret += sprintf(buf+ret, " brk:%u", info->icount.brk);	

	if (info->icount.overrun)
		ret += sprintf(buf+ret, " oe:%u", info->icount.overrun);

	/*
	 * Last thing is the RS-232 status lines
	 */
	ret += sprintf(buf+ret, " %s\n", stat_buf+1);
	return ret;
}

int su_read_proc(char *page, char **start, off_t off, int count,
		 int *eof, void *data)
{
	int i, len = 0;
	off_t	begin = 0;

	len += sprintf(page, "serinfo:1.0 driver:%s\n", serial_version);
	for (i = 0; i < NR_PORTS && len < 4000; i++) {
		len += line_info(page + len, &su_table[i]);
		if (len+begin > off+count)
			goto done;
		if (len+begin < off) {
			begin += len;
			len = 0;
		}
	}
	*eof = 1;
done:
	if (off >= len+begin)
		return 0;
	*start = page + (off-begin);
	return ((count < begin+len-off) ? count : begin+len-off);
}

/*
 * ---------------------------------------------------------------------
 * su_XXX_init() and friends
 *
 * su_XXX_init() is called at boot-time to initialize the serial driver.
 * ---------------------------------------------------------------------
 */

/*
 * This routine prints out the appropriate serial driver version
 * number, and identifies which options were configured into this
 * driver.
 */
static __inline__ void __init show_su_version(void)
{
	char *revision = "$Revision: 1.1.1.1 $";
	char *version, *p;

	version = strchr(revision, ' ');
	strcpy(serial_version, ++version);
	p = strchr(serial_version, ' ');
	*p = '\0';
 	printk(KERN_INFO "%s version %s\n", serial_name, serial_version);
}

/*
 * This routine is called by su_{serial|kbd_ms}_init() to initialize a specific
 * serial port.  It determines what type of UART chip this serial port is
 * using: 8250, 16450, 16550, 16550A.  The important question is
 * whether or not this UART is a 16550A, since this will determine
 * whether or not we can use its FIFO features.
 */
static void
autoconfig(struct su_struct *info)
{
	unsigned char status1, status2, scratch, scratch2;
	struct linux_ebus_device *dev = 0;
	struct linux_ebus *ebus;
#ifdef CONFIG_SPARC64
	struct isa_bridge *isa_br;
	struct isa_device *isa_dev;
#endif
#ifndef __sparc_v9__
	struct linux_prom_registers reg0;
#endif
	unsigned long flags;

	if (!info->port_node || !info->port_type)
		return;

	/*
	 * First we look for Ebus-bases su's
	 */
	for_each_ebus(ebus) {
		for_each_ebusdev(dev, ebus) {
			if (dev->prom_node == info->port_node) {
				info->port = dev->resource[0].start;
				info->irq = dev->irqs[0];
				goto ebus_done;
			}
		}
	}

#ifdef CONFIG_SPARC64
	for_each_isa(isa_br) {
		for_each_isadev(isa_dev, isa_br) {
			if (isa_dev->prom_node == info->port_node) {
				info->port = isa_dev->resource.start;
				info->irq = isa_dev->irq;
				goto ebus_done;
			}
		}
	}
#endif

#ifdef __sparc_v9__
	/*
	 * Not on Ebus, bailing.
	 */
	return;
#else
	/*
	 * Not on Ebus, must be OBIO.
	 */
	if (prom_getproperty(info->port_node, "reg",
	    (char *)&reg0, sizeof(reg0)) == -1) {
		prom_printf("su: no \"reg\" property\n");
		return;
	}
	prom_apply_obio_ranges(&reg0, 1);
	if (reg0.which_io != 0) {	/* Just in case... */
		prom_printf("su: bus number nonzero: 0x%x:%x\n",
		    reg0.which_io, reg0.phys_addr);
		return;
	}
	if ((info->port = (unsigned long) ioremap(reg0.phys_addr,
	    reg0.reg_size)) == 0) {
		prom_printf("su: cannot map\n");
		return;
	}

	/*
	 * There is no intr property on MrCoffee, so hardwire it.
	 */
	info->irq = IRQ_4M(13);
#endif

ebus_done:

#ifdef SERIAL_DEBUG_OPEN
	printk("Found 'su' at %016lx IRQ %s\n", info->port,
		__irq_itoa(info->irq));
#endif

	info->magic = SERIAL_MAGIC;

	save_flags(flags); cli();

	/*
	 * Do a simple existence test first; if we fail this, there's
	 * no point trying anything else.
	 *
	 * 0x80 is used as a nonsense port to prevent against false
	 * positives due to ISA bus float.  The assumption is that
	 * 0x80 is a non-existent port; which should be safe since
	 * include/asm/io.h also makes this assumption.
	 */
	scratch = serial_inp(info, UART_IER);
	serial_outp(info, UART_IER, 0);
	scratch2 = serial_inp(info, UART_IER);
	serial_outp(info, UART_IER, scratch);
	if (scratch2) {
		restore_flags(flags);
		return;		/* We failed; there's nothing here */
	}

	scratch = serial_inp(info, UART_MCR);
	serial_outp(info, UART_MCR, UART_MCR_LOOP | scratch);
	serial_outp(info, UART_MCR, UART_MCR_LOOP | 0x0A);
	status1 = serial_inp(info, UART_MSR) & 0xF0;
	serial_outp(info, UART_MCR, scratch);
	if (status1 != 0x90) {
		/*
		 * This code fragment used to fail, now it fixed itself.
		 * We keep the printout for a case.
		 */
		printk("su: loopback returned status 0x%02x\n", status1);
		restore_flags(flags);
		return;
	} 

	scratch2 = serial_in(info, UART_LCR);
	serial_outp(info, UART_LCR, 0xBF);	/* set up for StarTech test */
	serial_outp(info, UART_EFR, 0);		/* EFR is the same as FCR */
	serial_outp(info, UART_LCR, 0);
	serial_outp(info, UART_FCR, UART_FCR_ENABLE_FIFO);
	scratch = serial_in(info, UART_IIR) >> 6;
	switch (scratch) {
		case 0:
			info->type = PORT_16450;
			break;
		case 1:
			info->type = PORT_UNKNOWN;
			break;
		case 2:
			info->type = PORT_16550;
			break;
		case 3:
			info->type = PORT_16550A;
			break;
	}
	if (info->type == PORT_16550A) {
		/* Check for Startech UART's */
		serial_outp(info, UART_LCR, scratch2 | UART_LCR_DLAB);
		if (serial_in(info, UART_EFR) == 0) {
			info->type = PORT_16650;
		} else {
			serial_outp(info, UART_LCR, 0xBF);
			if (serial_in(info, UART_EFR) == 0)
				info->type = PORT_16650V2;
		}
	}
	if (info->type == PORT_16550A) {
		/* Check for TI 16750 */
		serial_outp(info, UART_LCR, scratch2 | UART_LCR_DLAB);
		serial_outp(info, UART_FCR,
			    UART_FCR_ENABLE_FIFO | UART_FCR7_64BYTE);
		scratch = serial_in(info, UART_IIR) >> 5;
		if (scratch == 7) {
			serial_outp(info, UART_LCR, 0);
			serial_outp(info, UART_FCR, UART_FCR_ENABLE_FIFO);
			scratch = serial_in(info, UART_IIR) >> 5;
			if (scratch == 6)
				info->type = PORT_16750;
		}
		serial_outp(info, UART_FCR, UART_FCR_ENABLE_FIFO);
	}
	serial_outp(info, UART_LCR, scratch2);
	if (info->type == PORT_16450) {
		scratch = serial_in(info, UART_SCR);
		serial_outp(info, UART_SCR, 0xa5);
		status1 = serial_in(info, UART_SCR);
		serial_outp(info, UART_SCR, 0x5a);
		status2 = serial_in(info, UART_SCR);
		serial_outp(info, UART_SCR, scratch);

		if ((status1 != 0xa5) || (status2 != 0x5a))
			info->type = PORT_8250;
	}
	info->xmit_fifo_size = uart_config[info->type].dfl_xmit_fifo_size;

	if (info->type == PORT_UNKNOWN) {
		restore_flags(flags);
		return;
	}

	sprintf(info->name, "su(%s)", su_typev[info->port_type]);

	/*
	 * Reset the UART.
	 */
	serial_outp(info, UART_MCR, 0x00);
	serial_outp(info, UART_FCR, (UART_FCR_CLEAR_RCVR|UART_FCR_CLEAR_XMIT));
	(void)serial_in(info, UART_RX);
	serial_outp(info, UART_IER, 0x00);

	restore_flags(flags);
}

/* This is used by the SAB driver to adjust where its minor
 * numbers start, we always are probed for first.
 */
int su_num_ports = 0;
EXPORT_SYMBOL(su_num_ports);

/*
 * The serial driver boot-time initialization code!
 */
int __init su_serial_init(void)
{
	int i;
	struct su_struct *info;

	init_bh(SERIAL_BH, do_serial_bh);
	show_su_version();

	/* Initialize the tty_driver structure */

	memset(&serial_driver, 0, sizeof(struct tty_driver));
	serial_driver.magic = TTY_DRIVER_MAGIC;
	serial_driver.driver_name = "su";
#ifdef CONFIG_DEVFS_FS
	serial_driver.name = "tts/%d";
#else
	serial_driver.name = "ttyS";
#endif
	serial_driver.major = TTY_MAJOR;
	serial_driver.minor_start = 64;
	serial_driver.num = NR_PORTS;
	serial_driver.type = TTY_DRIVER_TYPE_SERIAL;
	serial_driver.subtype = SERIAL_TYPE_NORMAL;
	serial_driver.init_termios = tty_std_termios;
	serial_driver.init_termios.c_cflag =
		B9600 | CS8 | CREAD | HUPCL | CLOCAL;
	serial_driver.flags = TTY_DRIVER_REAL_RAW;
	serial_driver.refcount = &serial_refcount;
	serial_driver.table = serial_table;
	serial_driver.termios = serial_termios;
	serial_driver.termios_locked = serial_termios_locked;

	serial_driver.open = su_open;
	serial_driver.close = su_close;
	serial_driver.write = su_write;
	serial_driver.put_char = su_put_char;
	serial_driver.flush_chars = su_flush_chars;
	serial_driver.write_room = su_write_room;
	serial_driver.chars_in_buffer = su_chars_in_buffer;
	serial_driver.flush_buffer = su_flush_buffer;
	serial_driver.ioctl = su_ioctl;
	serial_driver.throttle = su_throttle;
	serial_driver.unthrottle = su_unth